Moisture vapor barrier coating method

ABSTRACT

This invention relates to a method of preparing a moisture resistant packaging material comprising a cellulosic base material having printed matter on one side of the packaging material and on the same side as the printed matter, a primer coating composition and a top lacquer coating composition applied over the primer composition and wherein the printed matter, the primer coating composition and the top lacquer coating composition are applied to the base material using a gravure cylinder.

United States Patent 1 Hopermann Nov. 6, 1973 [54] MOISTURE VAPOR BARRIER COATING 3,132,041 5/1964 Pihl 117/76 P M THO 3,157,530 11/1964 Kane 4 3,205,093 9/1965 Lynch... [75] lnventor: Richard Konrad Hopermann, 224, 94 2 9 5 P lm r Oakland, NJ. 3,671,294 6/1972 Hopermann 117/76 P [73] Assignee: The Borden Company, New York,

NY. Primary Examiner-William D. Martin Assistant ExaminerM. R. Lusignan [22] Flled' 1971 Attorney-John L. Sigalos et al. [21] Appl. No.: 132,833

Related US. Application Data Division of Ser. No. 691,942, Dec. 20, 1967, Pat. No. 3,671,294.

11.8. C1 117/38, 117/33.3, 117/45, 117/76 P Int. Cl .1. 844d l/l6 Field of Search 117/15, 76 P, 80, 117/90, 92, 38, 45, 33.3

References Cited UNITED STATES PATENTS 11/1947 Carson l17/162X 57 ABSTRACT This invention relates to a method of preparing a moisture resistant packaging material comprising a cellulosic base material having printed matter on one side of the packaging material and on the same side as the 7 Claims, No Drawings MOISTURE VAPOR BARRIER COATING METHOD CROSS REFERENCE TO RELATED APPLICATIONS This application is a divisional application of Ser. No. 691,942, filed Dec. 20,1967, now U.S. Pat. No. 3,671,294, patented June 20, 1972.

BACKGROUND OF THE INVENTION Many packaged materials, such as detergents and potato chips, must maintain a substantially constant moisture content in order to prevent the development of undesirable characteristics such as lack of brittleness of potato chips. When the material in which these types of products were packaged did not function as an effective moisture barrier, the shelf life of the product was shortened due to the moisture gain or loss by the product.

When packing materials were used which functioned as an effective moisture barrier, such packaging materials were often prohibitively costly. I

It is an object of this invention therefore to develop a printing ink system which will be an effective moisture vapor barrier.

Another object of this invention is to enable normally unsuitable packaging materials to be used to package materials which require a substantially constant mois ture content.

Other objects and advantages will become apparent from the following more complete description and claims.

SUMMARY OF THE DISCLOSURE DETAILED DESCRIPTION The compositions of this invention comprise a primer 7 composition which is used to seal the pores of the packaging material.

The primer composition includes a resin and a solvent therefore. Generally, resins such as' vinyl halides and their copolymers and vinylidene chloride and'its rial as part of the printing ink system of this invention, a moisture vapor barrier is obtained which is a better barrier than when an equal number of coatings of an equal amount of either the primer composition or the top lacquer composition is applied tothe packaging material inplace of the system of this invention.

The resin of the primer composition is dissolved in a solvent. Generally, it is preferred that the solvent used for the primer composition be a ketone.

Among the solvents which may be used are methyl ethyl ketone, acetone, methyl isobutyl ketone, mesityl oxide, tetrahydro furan, cyclohexanone, isophorone, dimethyl formamide, and the like.

The amount of solvent used may vary up to about 85 percent by weight of the entire composition and preferably between about 70 to about 80 percent.

which might otherwise be affected by a degraded primer composition.

The amount of stabilizer added may vary up to about '20 percent by weight of the dry primer composition. It is preferred, however, to use up to about 8.5 percent. Caution should be exercised when using amounts in excess of 8.5 percent because as the amount used is increased appreciably above 8.5 percent the moisture barrier properties of the system may be adversely affected.

Among the stabilizers which can be used are epoxidized soy bean oils, oil modified sebacic acid, tin maleate, calcium maleate, barium maleate, 2(2'-hydroxy5- methylphenyl) benzotriazole, and the like.

A wax may also be added to the primer composition to enhance the moisture barrier properties of the syscopolymers may be used, dissolved in a solvent, to coat a and surface seal the pores of the packaging material.

The amount of resin used in the primer composition I is at least about 50 percent by weight of the dry primer composition. It is preferred however, to use between about 90 percent to 100 percent of the resin based on the weight of the dry components.

Among the resins which may be used are chlorinated, rubber The polyethylene wax compound mentioned above consists of the following components and is prepared in the following manner. vinyl chloride, vinylidene chloride, copolymers of vinyl chloride or vinylidene chloride with, for example, acrylonitrile, ethylene, propylene, vinyl acetate, and the like.

It has been found that when a top lacquer comprising I cyclized natural rubber is applied to a packaging matetem.

If a wax is present, it may be added in an amount up to about 15 percent by weight of the dry primer components. Amounts between about 3 percent to about 5 percent are preferred.

Any wax may be used which is soluble in the primer solvent at a temperature below the boiling point of the solvent and not in excess of 100C.

Among the waxes which may be used are montan wax, ceresin wax, sugar cane wax, Chinese insect wax, paraffinwax and blends of paraffin wax with the above as well as with microcrystalline wax, phenolformaldehyde resin and polyethylene. Synthetic waxes may also be used. For example, esters of ethylene glycol, diethylene glycol, polyethylene glycol, cetyl alcohol, stearyl alcohol, or sorbitol and the like with stearic, palmitic and myristic acids are satisfactory. Additionally, hydrogenated vegetable oils such as hydrogenated castor oil may be used as well as a Fischer-Tropsch wax, and the like.

The cyclized rubber of the top lacquer composition is also dissolved in a solvent. Generally, the top lacquer solvent will comprise between about 60 percent to about percent of the weight of the entire top lacquer composition. It is preferred however, to use an amount between about 65 percent to about 70 percent.

Any solvent may be used which is sufficiently volatile and which is compatible with the components of the top lacquer composition. It is preferred however, that the solvent used be an aliphatic hydrocarbon of up to about 12 carbon atoms such as hexane, octane, decane, dodecane, aromatic solvents such as toluene, xylene, benzene, and the like.

If desired, a wax may also be incorporated in the top lacquer composition. The waxmay be used in an amount up to about 20 percent by weight of the dry top lacquer composition. The waxes which may be used are those previously set forth in connection with the primer composition.

A drying agent may also be present in an amount of up to about 2 percent by weight of the dry top lacquer components and preferably up to about 1 percent. Although amounts in excess of 2 percent may be used, there is no advantage in using amounts greater than 2 percent.

Among the drying agents which may be used are, salts such as cobalt, manganese, lead, calcium, and the like, octoate, oleate, linoleate, resinate, stearate, naphthenate, ethylhexoate, lino-resinate, and the like.

An antioxidant may also be incorporated in the top lacquer composition. The antioxidant used preferably 7 should be one which is volatile enough to evaporate during the printing process. The antioxidant is used in an amount of up to about 10 percent by weight of the dry lacquer components and preferably up to about 3 percent. Among the antioxidants which may be used are oximes such as methyl ethyl ketoxime di-tertiarybutyl-p-Cresol, phenols such as 2,2-thiobis(4-methyl- 6,tertiary butyl phenol) and the like.

In order to more fully illustrate the nature of this invention and the manner of practising the same, the following examples are presented.

Unless specified otherwise, all weights expressed herein are based on the dry weight of the components present and exclude the weight of solvents.

EXAMPLE I All parts expressed herein are parts by weight unless indicated otherwise.

PART A PREPARATION OF PRIMER COMPOSITION To 23 parts of toluene in a reaction vessel is added 1 part paraffin wax. This mixture is heated slowly to increase the rate of solution of the wax. To this mixture is then added with agitation, a premix of 42 parts of acetone, 12 parts methylethyl ketone, two parts of tin PART B PREPARATION OF TOP LACQUER Two parts of paraffin wax by weight is added to a reaction vessel containing parts heptane. The mixture is heated to effect a solution and 4 parts of heptane and 31.5 parts of hexane are then added to the heated solution and dissolved therein. The solution is cooled and v 15 parts of a polyethylene wax composition is dissolved therein as is 26 parts of cyclized rubber.

To parts of heptane, 15 parts of the cyclized rubber are added and dissolved therein. Thereafter, 20 parts polyethylene resin is added and dissolved with the aid of agitation and heat.

PART C TESTING A clay coated board measuring 9 X 12 inches is coated with the primer composition using the gravure printing method to produce a coating of 1.5 lbs. per ream of paper. This coating is dried and a top lacquer coating is applied using the gravure printing method. The top lacquer coating is applied to a thickness of 0.75 lb. per ream.

The moisture vapor transmission rate of the coated board is tested using the test published in July, 1964 by the National Flexible Packaging Association and described as TR--l5. The moisture vapor transmission rate is found to be 1.2 grams of water vapor per 100 square inches per 24 hours.

PART D COMPARISON A clay board was coated to a thickness of 2.25 lbs. per ream using the gravure printing method and only the primer composition of Part A. The moisture vapor transmission rate is determined as aforedescribed and is found to be in excess of 2.5 grams per 100 square inches per 24 hours. This procedure is repeated using only the top lacquer composition of Part B to produce a coating of 2.25 lbs. per ream. The moisture vapor transmission rate of this coating when tested as aforedescribed is found to be in excess of 3 grams per 100 square inches per 24 hours.

EXAMPLE II EXAMPLE Ill The procedure of Example 1 is repeated several times. Each time the amount of resin used in preparing the primer composition is varied. The resin is used in amounts by weight of the dry primer composition of 50 percent, percent, and percent.

Good results are obtained each time.

EXAMPLE IV The procedure of Example I is again repeated except that the following waxes are used individually in the following amounts in place of the wax used in Example I.

Percent By Weight of the Wax Dry Primer Components parafi'ln wax 5 ceresin wax l0 Ester of ethylene glycol 15 and stearic acid mixture of 90% paraffin wax and 3 10% polyethylene mixture of 90% paraffin wax and 2 polybutene Good results are obtained in each instance.

EXAMPLE V calcium maleate in an amount of 2 percent based on the weight of the dry primer components, and oil modified sebacic acid in an amount of 16 percent based as aforesaid.

Good results are obtained.

EXAMPLE VI The procedure of Example I is repeated except that the wax used in Part B is varied. The wax used is is microcrystalline wax in an amount of 4 percent based on the weight of the top lacquer components.

Good results are obtained,

EXAMPLE VII The procedure of Example I is repeated except that 0.5 part of 68 cobalt octoate and 1 part of a ketoxime antioxidant are included.

Good results are obtained.

EXAMPLE VIII The procedure of Example I is repeated except that 0.1 part of 2(2'-hydroxy 5' methylphenyl)benzotriazole is included. v

Good results are obtained.

I claim:

1. A process of making a moisture resistant packaging material, said process comprising the successive steps of a. applying a layer of printing material, using a gravure cylinder, to a paper base material;

b. applying to the printed paper on the same side as the printed matter, using a gravure cylinder, a solvent solution of a primer coating composition consisting essentially of at least 50 percent by weight, based on the weight of the dried primer composition, of a resin of vinyl halide, vinylidene chloride,

primer composition, a top lacquer coating composition comprising at least percent of a cyclized natural rubber based on the weight of the dry top lacquer components; and e. drying the lacquer-coated paper. 2. The process of claim 1 wherein the primer composition includes an ultra-violet stabilizer in amount up to about 20 percent by weight.

3. The process of claim 1 wherein said top lacquer composition includes a wax in an amount of up to about 20 percent by weight.

4. The process of claim 1 wherein said top lacquer composition includes a drying agent in an amount up to about 10 percent by weight and an anti-oxidant in an amount up to about 10 percent by weight, said antioxidant being capable of volatilizing during the printing process. g

5. The process of claim 2 wherein the ultra-violet stabilizer is epoxidized soybean oil, tin maleate, calcium maleate, or barium maleate.

6. The process of claim 5 wherein said primer composition contains a wax which is soluble in the primer solvent below the boiling point of said solvent and up to C, said wax being present in amount of up to about 15 percent by weight.

7. A process of making a moisture resistant packaging material, said process comprising the successive steps of a. applying to a paper base material having printed matter on one side thereof, on the same side as the printed matter, using a gravure cylinder, a solvent solution of a primer coating composition consisting essentially of at least 50 percent by weight, based on the weight of the dry primer composition, of vinylidene chloride, a wax in an amount of up to about 15 percent and a stabilizer of epoxidized soybean oil or tin maleate;

b. drying the primer-coated paper;

c. applying thereto, using a gravure cylinder, over the primer composition a top lacquer composition comprising at least 70 percent of a cyclized natural rubber, based on the weight of the dry top lacquer components, a solvent therefor, a wax in an amount up to about 20 percent by weight, a drying agent in an amount up to about 10 percent by weight, and a volatile anti-oxidant in an amount up to about 10 percent by weight. 

2. The process of claim 1 wherein the primer composition includes an ultra-violet sTabilizer in amount up to about 20 percent by weight.
 3. The process of claim 1 wherein said top lacquer composition includes a wax in an amount of up to about 20 percent by weight.
 4. The process of claim 1 wherein said top lacquer composition includes a drying agent in an amount up to about 10 percent by weight and an anti-oxidant in an amount up to about 10 percent by weight, said anti-oxidant being capable of volatilizing during the printing process.
 5. The process of claim 2 wherein the ultra-violet stabilizer is epoxidized soybean oil, tin maleate, calcium maleate, or barium maleate.
 6. The process of claim 5 wherein said primer composition contains a wax which is soluble in the primer solvent below the boiling point of said solvent and up to 100*C, said wax being present in amount of up to about 15 percent by weight.
 7. A process of making a moisture resistant packaging material, said process comprising the successive steps of a. applying to a paper base material having printed matter on one side thereof, on the same side as the printed matter, using a gravure cylinder, a solvent solution of a primer coating composition consisting essentially of at least 50 percent by weight, based on the weight of the dry primer composition, of vinylidene chloride, a wax in an amount of up to about 15 percent and a stabilizer of epoxidized soybean oil or tin maleate; b. drying the primer-coated paper; c. applying thereto, using a gravure cylinder, over the primer composition a top lacquer composition comprising at least 70 percent of a cyclized natural rubber, based on the weight of the dry top lacquer components, a solvent therefor, a wax in an amount up to about 20 percent by weight, a drying agent in an amount up to about 10 percent by weight, and a volatile anti-oxidant in an amount up to about 10 percent by weight. 